Arsenal have re-signed Thierry Henry from New York Red Bulls on loan for a short-term period.

Henry, now 34, left Arsenal for Barcelona for £16.1m in June 2007. The striker then went on to the MLS with New York Red Bulls three years later.

Arsenal manager Arsene Wenger told his club’s official website: “I am very happy. It was my desire and Thierry’s desire. We will have Thierry for January and in February. Then he will go back to the United States. I am sure during these two months he will be a massive asset to the team in the dressing room and on the pitch. He can be relaxed, not under too much pressure and be a tremendous help to the team.”

Henry added: “It is unreal to be honest. But when it comes to Arsenal my heart will always do the talking. Once I knew the plan behind it I was OK with it. I am not coming here to be a hero or prove anything. I am just coming here to help. People have to understand that. Marouane [Chamakh] and Gervinho are going to the Africa Cup of Nations, so I was asked to fill in the gap. It is a loan deal and I’ll be on the bench most of the time. If I can make the bench that is! The Boss has a team here already who are doing something good. I am just going to be part of the squad.

The Frenchman continued: “I want to send a message to the fans of New York Red Bulls as well. I always said I would not play in Europe again. But it is hard for me when it comes to Arsenal. I am not coming here for the whole season, I will be back and I want to win the MLS Cup with the Red Bulls. I hope it is a win-win situation where I can help Arsenal and come back fit for the MLS season.”

Arsenal have strengthened their defence with purchase of Werder Bremen defender Per Mertesacker.

The North London club have not disclosed details of the fee or contract length.

Arsenal manager Arsene Wenger told his club’s official website: “We are delighted to welcome Per Mertesacker to the Club. He is a German international with vast experience and strength and is good on the floor and in the air. I believe he will be well-suited to the Premier League and a tremendous asset to the team.”

The 26-year-old defender added: “I had a great time at SV Werder Bremen and I’m grateful to the club. Moving to London enables me to fulfil a dream and a further step in my career. The Premier League has always represented a great challenge for me.”

Arsenal have brought in Monaco striker Chu-Young Park. No fee or contract length has been disclosed for the 26-year-old South Korea international.

Arsenal manager Arsene Wenger told his club’s official website: “We are delighted to have signed ‘Chu’. He will add true quality to our attacking forces and will be a valuable addition to the squad.”

Chu-Young Park added: “I am very honoured and I feel very happy to be at Arsenal. It is a dream to be here and I am really proud to be an Arsenal player. Now I just want to show how good I am and prove myself.

“In my opinion this is a great club, now I have to show what I can do on the pitch. I will do my best, I will never give up, I will show heart, I will give everything and I hope [the fans] will support me.”

Queens Park Rangers have made another swoop in the transfer market by signing Arsenal left-back Armand Traore for an undisclosed fee.

The 21-year-old, who has one cap with Senegal, has penned a three-year contract at Loftus Road.

QPR manager Neil Warnock told his club’s official website: “Armand has been my number one defensive target for a while now. I’ve been speaking to [Arsenal manager] Arsene [Wenger] for a couple of weeks.

“He’s a young and exciting lad who I think can only get better playing for a side like ourselves on a regular basis. He needs games and he’ll get that here.

“Nobody has seen the best of him yet, but over the next couple of years I’m confident he’ll show the quality that I clearly believe he has.

“He’ll be a great outlet for us down that left hand side.

“He’s got all the attributes you need to be a top, top defender.”

Traore added: “When I talked to Neil Warnock he was very passionate about what I could bring to the Club.

“He was very motivated about playing me week in, week out, and that’s what I need at this stage of my career.

“I’ve not been able to prove and show what I’m all about because I’ve been at two big, big Clubs like Juventus and Arsenal.

“I’m looking forward to coming here and playing regular football.

“The ambition of the new owners and the calibre of players they are signing is something that really attracted me to the Club.”