Donald Trump has said used the attack on a mosque in Egypt to make the case for building a wall with Mexico and a travel ban from countries vulnerable to terrorism.
At least 235 people have been killed after a gun and bomb terror attack at a packed mosque in Egypt's North Sinai province today.
In the aftermath the atrocity he tweeted: "Will be calling the President of Egypt in a short while to discuss the tragic terrorist attack, with so much loss of life. We have to get TOUGHER AND SMARTER than ever before, and we will. Need the WALL, need the BAN! God bless the people of Egypt."
Another 130 people are reported to have been injured, making it the worst terror attack in the country's modern history, reports Daily Mail.
The terrorists reportedly detonated a bomb in the mosque's creche before firing on fleeing worshippers while blocking escape routes with burnt-out cars.
Egypt's military has begun conducting air strikes around the area of North Sinai, security sources and eyewitnesses said.
The strikes have been concentrated in several mountainous areas surrounding Al Rawdah mosque where militants are believed to be hiding out, the security sources said.
The suspected Islamic State attack took place at the Al-Rawdah Sufi mosque in Bir al-Abed, near El-Arish, during Friday prayers. Extremist Sunni jihadists have previously targeted Sufis - a mystical Islamic sect - for deviating from orthodoxy.
In a televised address the president said: 'The armed forces and the police will avenge our martyrs and restore security and stability with the utmost force.
"What is happening is an attempt to stop us from our efforts in the fight against terrorism, to destroy our efforts to stop the terrible criminal plan that aims to destroy what is left of our region."
US President Donald Trump, meanwhile, condemned the mass murder as a "horrible and cowardly terrorist attack on innocent and defenseless worshipers", adding: "The world cannot tolerate terrorism."
An improvised explosive device (IED) is believed to have been used before it was followed up with machine gunfire from multiple gunmen using four off-road vehicles.
A witness said: "They were shooting at people as they left the mosque.
"They were shooting at the ambulances, too."
Some reports have claimed the bomb was set off in the children's kindergarten area of the mosque before the terrorists - in military uniforms and wielding black flags - slaughtered those who fled.
They added that IS militants had blocked escape routes from the area by blowing up cars and leaving the burning wrecks blocking the roads.
Another report claims that terrorists wearing suicide vests hid themselves among the people at the mosque before detonating the bombs, but this remains unconfirmed.
MP Mustafa Bakri branded the situation "catastrophic" on Twitter.
He added: "The terrorists wore masks and surrounded the mosque during prayers, and terrorists wearing belts were hidden among the worshippers."
A tribal leader and head of a Bedouin militia that fights Islamic State said that the mosque is known as a place of gathering for Sufis.
The Islamic State group shares the puritan Salafi view of Sufis as heretics for seeking the intercession of saints.
MENA reported that Egypt's presidency declared a three-day mourning period for the attack, as President Abdel-Fattah el-Sissi convened a high-level meeting of security officials.
An angry President al-Sisi pledged to respond with "brutal force" against militants who massacred at least 235 people at a mosque during weekly prayers on Friday.
"The army and police will avenge our martyrs and return security and stability with force in the coming short period," he also said in a televised speech.
Cairo's international airport boosted security following the attack, with more troopers and forces seen patrolling passenger halls, conducting searches and manning checkpoints at airport approaches.
Resident Ashraf el-Hefny said many of the victims were workers at a nearby salt firm who had come for Friday services at the mosque, which had contained some 300 worshipers.
"Local people brought the wounded to hospital on their own cars and trucks," he said.
British prime minister Theresa May said she was "appalled by the sickening attack", which she declared an "evil and cowardly act".
UK foreign minister Boris Johnson, meanwhile, condemned the "barbaric attack" in a post on Twitter, while his French counterpart Jean-Yves Le Drian expressed his condolences to the families of victims of the "despicable attack".
Ahmed Abul Gheit, head of the Arab League, which is based in Cairo, condemned the "terrifying crime which again shows that Islam is innocent of those who follow extremist terrorist ideology," his spokesman said in a statement.
The jihadists had previously kidnapped and beheaded an elderly Sufi leader, accusing him of practising magic which Islam forbids, and abducted Sufi practitioners later released after "repenting."
The group has killed more than 100 Christians in church bombings and shootings in Sinai and other parts of Egypt, forcing many to flee the peninsula.
The military has struggled to quell the jihadists who pledged allegiance to IS in November 2014.
IS regularly conducts attacks against soldiers and policemen in the peninsula bordering Israel and the Palestinian Gaza Strip, although the frequency and scale of such attacks has diminished over the past year.
They have since increasingly turned to civilian targets, attacking not only Christians and Sufis but also Bedouin Sinai inhabitants accused of working with the army.
Aside from IS, Egypt also faces a threat from Al-Qaeda-aligned jihadists who operate out of neighbouring Libya.
A group calling itself Ansar al-Islam - Supporters of Islam in Arabic - claimed an October ambush in Egypt's Western Desert that killed at least 16 policemen.
Many of those killed belonged to the interior ministry's secretive National Security Service.
The military later conducted air strikes on the attackers, killing their leader Emad al-Din Abdel Hamid, a most wanted jihadist who was a military officer before joining an Al-Qaeda-affiliated group in Libya's militant stronghold of Derna.
Reacting to the news, Britain's ambassador to Egypt, John Casson, tweeted: "I am disgusted by the evil attack that killed & injured so many Egyptians in Sinai today. On behalf of the UK my deep condolences to all involved.
"These attacks on people praying in mosques & churches only strengthen our determination to stand together, & defeat terrorism & hate."