WASHINGTON – US President Barack Obama twice convened his national security team this week to review operational movements by Islamic State and its public threats to the US homeland, he said from the White House Wednesday.Assuring the American people as they prepare to celebrate Thanksgiving – one of the busiest periods of travel of the year – the president left a briefing in the Situation Room declaring he had seen no specific, credible threats against the country. He promised to inform the public should one arise.The president’s briefings came on the heels of a worldwide travel alert to American citizens issued by the State Department on Monday night, which requested travelers remain alert in crowded spaces.The alert specifically warned of the continued threat from Islamic State shortly after the group orchestrated a series of attacks across Paris. The group released two videos threatening to attack Washington and New York shortly after those strikes.“I think all of us recognize how horrific and heinous what took place in Paris was,” Obama said, flanked by his national security staff in the Roosevelt Room. “Given the shocking images, I know that Americans have been asking each other whether its safe here.”“It’s understandable that people worry something similar could happen here,” he said.“So as we go into Thanksgiving weekend, I want the American people to know that we’re taking every possible step to keep the homeland safe.”The first meeting on Tuesday, within hours of the president hosting France’s President Francois Hollande at the White House, was attended by his full National Security Council.Obama “was briefed that there is currently no specific, credible threat to the homeland from ISIL,” according to a notice of the meeting, referring to the Islamic State by its government acronym.“The president directed his national security team to continue to intensify ongoing efforts to degrade and destroy ISIL,” it continued, “including working with our partners to increase our military cooperation in the counter-ISIL campaign, disrupting foreign fighter networks, halting ISIL expansion outside of Syria and Iraq, and disrupting any ISIL external plotting efforts.”Obama said US counterterrorism officials, military and intelligence alike, would be “working overtime” through the holiday, “continually monitoring threats at home and abroad.”They are “vigilant, relentless and effective,” he said.Increased security was visible starting on Tuesday at the country’s most trafficked train stations and airports. The Obama administration fears that extremists loyal to Islamic State may coordinate an attack using encrypted messaging technology, near impossible for government agencies to detect.“It is in our capacity to roll up those networks,” Obama said on Sunday on a trip to Malaysia.But he added: “Sadly, it turns out that if you’re willing to die, you can kill a lot of people.”One video threat against New York released last week by ISIS featured images of Herald Square, known for its role in the Thanksgiving Day parade.