President Trump, asked if he'll tell Russian President Vladimir Putin not to meddle in the 2020 election, told reporters Wednesday what he says to Putin is "none of your business." Mr. Trump made the comments on his way to Japan for the G20 summit, where he'll meet with Putin and other world leaders.

Mr. Trump continues to be criticized for his handling of relations with Russia, recently making headlines for telling ABC News he would probably take a look at information from foreign governments that could hurt his opponents. He'll be meeting with Putin on the sidelines of the G20 summit, and it's unclear how much of the content of that meeting will be shared.

As he departed the White House for his trip to Asia Wednesday, Mr. Trump also expressed optimism about progress on a humanitarian border aid bill.

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"We are moving along very nicely with a bipartisan bill in the Senate," he told reporters at the White House. He spoke with House Speaker Nancy Pelosi before he departed and said, "I think that Nancy wants to get something done."

However, the bill in the Senate differs from the House version, and Senate Majority Leader Mitch McConnell has been critical of the measure passed by the House Thursday, calling it a "go-nowhere proposal filled with poison-pill riders which the president would veto."

The president was also asked about a photo depicting the tragic death of a migrant father and his two-year-old daughter, who drowned trying to cross the Rio Grande this week. He said that if Congress "fixed the laws," this wouldn't happen. And he noted that the river currents can be rough. If we had the right laws, he said, "those people wouldn't be coming up...they wouldn't be trying" to come to the U.S.

In Japan, Mr. Trump is expected to meet with Chinese President Xi Jinping and Putin, among other world leaders. The international trip comes amid escalating tensions with Iran and as a trade deal with China still has yet to come to fruition.

On Tuesday, Mr. Trump threatened the "obliteration" of parts of Iran if it attacks anything belonging to the U.S. Mr. Trump authorized new sanctions against Iran's supreme leader and a cyberattack on Iran after Iran shot down a U.S. drone last week.

"Iran's very ignorant and insulting statement, put out today, only shows that they do not understand reality," Mr. Trump tweeted Tuesday morning. "Any attack by Iran on anything American will be met with great and overwhelming force. In some areas, overwhelming will mean obliteration."

Mr. Trump arrives in Osaka, Japan, on Thursday night for the G20 summit and a host of sideline meetings Then on Saturday he flies to Seoul, South Korea, to meet with South Korean President Moon Jae-in. He will return to D.C. on Sunday.

Kathryn Watson and Arden Farhi contributed to this report.