SEOUL, April 17 (Reuters) - U.S. Vice President Mike Pence put North Korea on notice on Monday, warning that recent U.S. strikes in Syria and Afghanistan showed that the resolve of President Donald Trump should not be tested.

Pence and South Korean acting president Hwang Kyo-ahn, speaking a day after a failed missile test by the North and two days after a huge display of missiles in Pyongyang, also said they would strengthen anti-North Korea defenses by moving ahead with the early deployment of the THAAD missile-defense system.

Pence is on the first stop of a four-nation Asia tour intended to show Americas allies, and remind its adversaries, that the Trump administration was not turning its back on the increasingly volatile region.

Just in the past two weeks, the world witnessed the strength and resolve of our new president in actions taken in Syria and Afghanistan, Pence said in a joint appearance with Hwang.

North Korea would do well not to test his resolve or the strength of the armed forces of the United States in this region, Pence said.

The U.S. Navy this month struck a Syrian airfield with 59 Tomahawk missiles after a chemical weapons attack. On Thursday, the U.S. military said it had dropped the mother of all bombs, the largest non-nuclear device it has ever unleashed in combat, on a network of caves and tunnels used by Islamic State in Afghanistan.

North Koreas KCNA news agency on Monday carried a letter from leader Kim Jong Un to Syrian President Bashar al-Assad marking the 70th anniversary of Syrias independence.

I express again a strong support and alliance to the Syrian government and its people for its work of justice, condemning the United States recent violent invasive act against your country, Kim said.

On a visit to the border between North and South Korea earlier in the day, Pence, whose father served in the 1950-53 Korean War, said the United States would stand by its iron-clad alliance with South Korea.

All options are on the table to achieve the objectives and ensure the stability of the people of this country, he told reporters as tinny propaganda music floated across from the North Korean side of the so-called demilitarized zone (DMZ).

There was a period of strategic patience but the era of strategic patience is over.