NEW YORK - Two Pakistan-born brothers have pleaded guilty to federal terrorism charges, admitting they plotted an attack on landmarks in New York City and later assaulted two deputy US Marshals while in custody, according to US media reports.

Raees Alam Qazi, 22, and Sheheryar Alam Qazi, 32, both pleaded guilty in federal court in Miami to one count of conspiring to provide support to terrorists and conspiring to assault two federal employees, the reports said.

The younger brother pleaded guilty to an additional charge of attempting to provide material support to the al Qaeda.

The bearded Qazi brothers, who wore beige prison scrubs and were handcuffed, shackled and under tight security in court, both said “guilty” when asked how they wanted to plead.

The brothers were arrested Nov 29, 2012, in Broward County.

Raees Qazi admitted he had spent a few days bicycling around Manhattan to scope out potential targets that would result in mass casualties, according to the FBI and US Attorney’s office.

In this plea agreement, Raees Alam Qazi admitted to travelling to Manhattan in 2012 to scout major landmarks and set off a massive bomb.

He aborted the mission when he ran out of money.  

He was arrested after returning to Broward County, Florida, where the brothers lived, according to CBS News.

The men previously pleaded not guilty to several terrorism-related charges, including conspiracy to provide material support.

The brothers are also charged with assaulting two US Marshals while being escorted in the Miami court complex.

On Thursday, they both plead guilty to that charge.

They were originally charged with attempted murder of the Marshals, who they punched and wrestled with while chanting “Allah-o-Akbar”. “And that was crafted in such a way that they would not face up to life in prison, in addition to the terrorism charge,” said Jay Weaver, Miami Herald’s federal courts reporter.

The Attorney for the older brother was quoted as stating that they knew they didn’t stand a chance at trial.

“He decided to enter a guilty plea. As he told the court, he did so because he was in fact guilty,” said Attorney William Barzee.

Federal prosecutor Karen Gilbert said on Thursday, terrorism Internet sites “encouraged brothers in the West to conduct violent Jehad and how to select targets in the attack.”

She also said that the younger brother “conducted intense computer research regarding al Qaeda and weapons of mass destruction.”

Prosecutors said the brothers planned to use Christmas tree bulbs as explosives.

The two brothers were caught by the controversial National Security Agency cell phone monitoring system.

Federal agents taped them communicating with al Qaeda in the Middle East.

They were angry that US drones were attacking terrorists in Pakistan. Key evidence includes FBI wiretap and other communications intercepts. Prosecutors and the defence recommended the siblings get 17 years.

“We made a joint recommendation on the plea agreement and we think it is the appropriate sentence for the conduct that the defendants engaged in,” said Gilbert. But on Thursday, the judge made it clear, she’s in charge, asking the brothers, “In regard to any recommendation as to sentencing, do you understand that I can reject that and impose a punishment more severe?”“Yes,” the brothers replied.

Raees Alam Qazi faces up to 35 years behind bars while Sheheryar Alam Qazi faces upto 20 years in jail. Though Sheheryar Qazi did not know all of the precise details, he knew that his brother was actively planning to set off a bomb in Manhattan and provided emotional, financial and practical support, authorities said.