President Donald Trump is in Saudi Arabia as he begins his first major international trip of his second term, focusing on economic agreements and regional concerns, including Iran's nuclear program and U.S. relations with Syria.Saudi Arabia welcomed Trump with a grand reception after Air Force One landed on Tuesday. The president is kicking off his four-day trip to the region by outlining his vision for the Middle East. "Forging a future where the Middle East is defined by commerce, not chaos," Trump said.Ahead of the investment conference, Trump signed more than a dozen economic and bilateral cooperation agreements between the U.S. and Saudi Arabia. Gordon Gray, a professor at George Washington University, said, "We've already seen some deals announced in terms of arm sales."Following the Crown Prince's commitment of $600 billion in new Saudi investments in the U.S., Trump is pushing for more. "But the 600 billion, knowing you, will be a trillion dollars. You'll try to get us there," Trump said.During his speech, Trump issued a warning to Iran, urging its leadership to take a deal to limit its nuclear program. "If Iran's leadership rejects this olive branch and continues to attack their neighbors, then we will have no choice but to inflict massive maximum pressure," he said.Trump also announced the lifting of sanctions on Syria's new government "in order to give them a chance at greatness."Meanwhile, concerns are growing back home about Trump's plan to accept a $400 million plane from Qatar, free of charge. Senate Minority Leader Chuck Schumer is now vowing to hold up all political nominees to the Department of Justice until Congress gets more answers, adding, "This is not just naked corruption, it is also a grave national security threat."After visiting Saudi Arabia, Trump will head to Qatar and then the UAE. The White House announced on Wednesday that he will meet with Syria's new president, who led the overthrow of Bashar Assad last year.