Shortly after a ceasefire took effect in Gaza, clashes erupted between armed groups, some backed by Israel and others loyal to Hamas, as the Islamist movement sought to reassert control over the devastated territory.

By Alexander Cornwell and Nidal al-Mughrabi KIRYAT GAT, Israel (Reuters) -The U.S. increased pressure on Hamas on Tuesday to disarm in the next phase of an already fragile Gaza ceasefire as President Donald Trump pushed to cement an end to the devastating conflict.

U.S. Secretary of State Marco Rubio on Friday toured a U.S.-led center in Israel overseeing the Gaza ceasefire, as the Trump administration worked to set up an international security force in the territory and shore up the tenuous truce between Israel and Hamas.

Hamas has deployed hundreds of police and clashed with armed groups in Gaza in what the militant group says is an attempt to restore law and order in areas where Israeli troops have withdrawn for the U.

Israel said it carried out air strikes on Gaza Oct. 19 after its troops were attacked, sending the ceasefire into uncertainty.

Trump said on Monday that the US would destroy Hamas if the militant group didn’t continue to honor the ceasefire with Israel.

The Gaza ceasefire plan means whatever President Donald Trump says it means. His envoys need to focus on ending the mass starvation of Palestinians.

Israel and Hamas took steps toward ending the two-year war that has devastated the Gaza Strip, but hard work lies ahead.

Secretary of State Marco Rubio has been meeting with U.S. military personnel in the Middle East as they monitor the fragile Israel-Hamas ceasefire. CBS News' Holly Williams has more.